SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90e01277b4bd0b696e08d300d860eb67f2ee15968778c02e13bdba04e6afa20a' 
  AND token = 'z4YHVRok1xWLGz971Z9rPh/TeMgSLErrXPhUIQ8WAfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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