SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '256cc6b87bc65e65d7c70a254fe14addcf974f2087a0cfd92874ef92562561cd' 
  AND token = 'WaBfJSVhe/ysLlMRR91MT1rvLVwHtlXrM0r4L6axTnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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