SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8549f6b962c3372fa4f35c2744eb55246244a730429aa71d4134aa88ae193847' 
  AND token = 'bmvCNvrfx/mVmMZtVaZ6BBEqZGfeFLDeMAAm0o+MjaA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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