SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5e4f21bc82664adda3e258aeb9536b0543e6c14d07a8dd5fe06552ab4110abf' 
  AND token = 'i8sCrqz/aUUqqIQW9HZ2Kigu/T39MDVeVjj9YGIUVk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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