SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aaaadc3631774bc9bdd09bd33836221105b9506f3bc794b87fa6988a39b0f8e5' 
  AND token = 'PrcoasvJmfzhtAr5NTSjXUy/Xjhtv1Sc5nH5PoM4s+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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