SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb1c3602f76de2dbf5dd9adb98b44056568ab93c34c15d62ef36f027679deb9a' 
  AND token = '5W6rp08OLfC3MxIp+51RRFxXtL0bhqCTl/nBj7AyidE=' 
  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"
    }
  }
}