SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56b0f697164de246837470108c6d3cfc50be4d288443b2656333fed53dbde2b4' 
  AND token = 'dcyWB18z0ctqDsIzMiSp6jqaoIPODn8nX90VAhA9oNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}