SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c044f838bd223230b792d69969251243af6e6eba97bd4a1f369bcbbbba1a38c' 
  AND token = '65Rb+EYm6mlxlP4aEYdyQ/D8wxK42mOuwEDgWedXuVc=' 
  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"
    }
  }
}