SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c395fca3cc496447ce8b8d88486e2b00c03c4e8423bdede3077aac7e085a320e' 
  AND token = 'EtcJmJtc/R/spd9MbxlrFdm4VZRWEimkSnXJjjJDduQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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