SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '808cac4af29f77ac7da6b75548b86de595d721e9dd9b729de84a6a2e2197562d' 
  AND token = '/8uDvL71kcv0VNGuJvDyZhbRJE90mGFch8TptYIB+iM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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