SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9f6cf7ae5eb30cc5f9093fa9397af18c42e699179693355355f087ed9a64986' 
  AND token = 'uCa0UZLxCMGS4KQWtjPD9ixtYPa5VYPDGETTLMEq4jg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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