SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ee0ac3490f244557bc55b791e4cc988cb10f9723e9f8f57ff28f5a5345ac468' 
  AND token = 'JnZMgxDTCArQa/9xSZtHiR02bBtiWlKAuLayB090PeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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