SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c4a2b3bbaa9779bc6f6143d9f71dd93100141027bff295edea9b8bf2b53dba2' 
  AND token = '1/XyzoEbkHpi6w9KIwYyW0OsWTZDqV+p5Bne1slqmK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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