SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5249afecda853caf3598f8ef385d3f33061bb6b0d294367afec8977c3306b97b' 
  AND token = 'y5gHRHCpRdASfGf13+5t5R/bVzgH+e9mJ5ChYNun/HQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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