SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c09a7b81f0a0dce1cdd492cb6f174f70adcd95aebed2442907e8faa077faeb5a' 
  AND token = '4BJmvb5NbtqcGiDpYhWpMfHRdvnGrhFMMfhSGv/dGIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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