SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5acff6bff24e2fb9329fbfc00875e0313d4d7c7af16063e946881b53bdfdf308' 
  AND token = 'PZ3Fq54Pl+IyNUmTPv3em0K/NFp4HLXAYlxcNjdmCuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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