SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ae5955cfcd6c2aeda7465c8ce68b65e8f508493559fc092f0eec502d509f87' 
  AND token = 'A8DX8K8YhY9caRBjq5r+ghpD7SyBfRZjDMU+bjo6sME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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