SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57c30f321e16185db64dd0879585beb5153c8745788f18dfba2b56c9fd751c2c' 
  AND token = 'yvvgvPUgiOAouhckQ7Q+nOmYCSQ4BzjtwbKEx8TtO0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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