SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b26ecf63785ccd1eb8300a5dd0f2bfbcac880f9cc37efc41fc38db23e5781bf' 
  AND token = 'WvXWsH0+P0MaNxAhqoqd0QuzFAFpHIQpqmXCEp+MoTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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