SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ec67ffee4a5099fe0b1eacba1a38be25a659ed840625f0ccbf6f15aa551adc1' 
  AND token = 'rcoVTfqrQmt0kQVWQZjebv4lHvJHoIz2EtGASNm3bz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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