SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7c5e0afec5ef9511856d15134a77970609abcfc8ec722587fcaaba68cd63742' 
  AND token = 'tcmxGhem+UDCvVyRTZgKCRNQh6AuoCcT7YA2wWmgmNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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