SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '768b76760c1e00a1bd93d7f2eb8fa84b684c2d0285bfff69594b91da7f11d37d' 
  AND token = '4t8InqFTvB3TPCZlf9YnqjqWcoXTK+3r3chYAKzP8Kc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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