SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1a7a395c9399fd85094f048a12314f4a1eda2dd162722fc0e8c1b8b4ae5c71b' 
  AND token = 'Qj7tuE2eNctp+omnRqRFX2xf+Vp0zknA01fNX9HFyBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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