SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '931b6afa74dbfae617f8f318a49b25cf7a3e9fb42dd911ad05485ac0348f0af1' 
  AND token = 'RD9smm1wCfjLLq/2F0IUZlau40kWJZiO6oj1elYhghQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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