SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '877ca97f776c674da1e22707d4da073b101b56a6edcb324da34b6c282ac8623c' 
  AND token = '7qhYzvtbCOEl23jYsPKMhalOnfRBRU6LA8w5D+GG+Fw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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