SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58c35a93edd9e2f0007ebe41d413a6125387594969d428e1c82eadf9ad68d9d4' 
  AND token = '56CYCxhL1ikyDFy4rklWRqO6AXK4jtYqtgJZBiwuVmI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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