SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb8158770fcd70fcaad4194d2e66f72f508a3afa5b63bd073199ed5098baabd1' 
  AND token = 'kL5KcGeXB08e5e6btMXIdOUuooJF1g9J8Nixg46GHJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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