SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c528f0284706270d1918d3b45fb5de657b519467a75cb36dd3538b86df29dc55' 
  AND token = 'PSjANYtSAuoGZP2oecZDxfivTSCf3IYCH0S0AJbGaq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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