SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ee18adba04d44b8a3453f424c9fe44a03b37093516dcadeeecd02fa931d884e' 
  AND token = '+UPJehbS4QwroUg79QV8z1KCIKfbzHGQCpvs+k0KiLY=' 
  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"
    }
  }
}