SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bc650019ca4521eb596c2ef3d26011e16dc70477b123071579eaad258eb3e15' 
  AND token = 'ixy2X+cGL2cwe4zAxMCJbUIEu1w8ai0WY0MGxqE77WA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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