SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab8f4952528a627333bd55aff29dd625a1b666543a5f8e992e68c4e0389773aa' 
  AND token = 'qc3CiOe/fm8vHupnZDNm3E+sdXXlYNgUhSgWHXrfEUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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