SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '548d5bdcf1a54c695dfb57f5992a0955b3135adde03b3e6cb88e216f730940d0' 
  AND token = 'KQHRS82QRDZRqpXLAV+Ta6fPyhPFJUeOOZmqnWGrAJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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