SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd884fc4a29ae275ee0f2e939f551525b52936f8a54746da3d559fd8bf18c8c6' 
  AND token = 'gQB/XVlD93d8K+0qWtTAtXSTVw5qJV7+nBcRbS/BDbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00104

JSON explain

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