SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d766f376f62bb84535cb7809b48d69eb95057e1a1836f185d46aa52aa4469dc' 
  AND token = 'SrsTundZOYarhm435L1fUVNmXvTfHg9HRl0IIyn/C2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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