SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c2c52708278b7b7aaaedd40a06687d46da1d73af74ba3d0abf81b398a2aac1c' 
  AND token = 'nLm2hyMp/NZYpDRgdwTZR+f66YhPQ+yEvqwcBjmUGyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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