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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c979e1ac0aa16f345fb1838b3e4903293d0c0ff7b8a4c60a0ecc014ed7f56573' 
  AND token = 'vPQcUORYmtb6ibsiyp4RoSwQR0/x1imDrFyYF7iM/5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}