SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e254aeaa6404291dd169a081be7e0aade523ed8f14f9bb7f01c0321b595045ae' 
  AND token = 'yfaMtTm4B1YODCR3E4awHb12+fYApeEPhCGsRizaPsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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