SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '259f2071a1906e626f829616a3fb9f625f1d57ae1e760742e1665b90d438ca47' 
  AND token = 'Hk+z1+rBb3R6B6YvzqjvgZYU2QIQIcnDUmv4ambqfR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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