SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56666ddaf0538df63dfafc744c8194e2ce84e7fdb97d1f395864d25a8c57f198' 
  AND token = 'MxOq6+FNnQwOFxlWmfYhLpuDJ3Zrttygb3G2yDCRZN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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