SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c31aa1f88109568af43f433cd426252e727764605bd82993888da104267a829' 
  AND token = 'S5URkuYf96mSJGt2auVqBxrtWRCDBt70qSqfYN5Ytcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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