SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de7926629fcec2f92ba188932325862973250fd553ede653db1a19f9ca32caed' 
  AND token = 'maeAovLVrccJtkP/Aj4MFZRcqBasup+hZwFgC4O8M0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00065

JSON explain

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