SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7209c712582c66382f90a040692cdb7d497b279414ca89d27edea2ef61e36df' 
  AND token = '8ItVd8QASnidpmSITkCLarcvzbibOyZ4TGrKAjN33Zw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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