SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8fb698a832e051dd74da4f667763234327af54f7582dac34129270c6407b83b' 
  AND token = 'NIGYcatsbAB7SEBVMim7i1h1GqIcoOWGQWp8QZhLSAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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