SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '950b8becd64504879510070c061748f17a4e3d43db52716301688e444bbf752c' 
  AND token = 'bavxzpom51UOWF4r0vZN6SkoAQmsyzgrs9ehxwrNflg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}