SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be102c31783abf37d82865929247a4fe4c76a5450a9df0df0d46fbced709cc81' 
  AND token = 'cRE5uMm2HFPc6Z3WTeLYbtwZZj+pBBB5MwmwIKhHd5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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