SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f047cf1c274b03283ca8c5a9507edd8034f19e6fe3b87bd10315f4eb54c30cf9' 
  AND token = 'XOIUpMiJmW/dQq2lAbNWfRhBa6tSfXpn23gsWGlBCQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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