SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eaf3d783e83ec285f2cbb8bf999e01c40047f85edf85603d18fc0c47a9238a69' 
  AND token = '0LVaLSgPpzxg2Ql+MQZ28TY/hzLv+VSZSHGI7tMMRpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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