SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c3123f66bb741942d3f05097ea18b8e30fdb932e1bb98450eb789bf14baa568' 
  AND token = 'ti6c0rzXXIfKsz+QacU/gZchopaurU1tLIbftvG0uDM=' 
  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"
    }
  }
}