SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb9b72cb0e4bccd49ecc2c9942168618bd373279766b584d6471da575d44adbf' 
  AND token = '+X978lVKWIn1Psw+cJ6BOk/wyrvWIwDNm7d3+bUPKpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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