SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b9a68514690426ac922b08c0efbde07aa544d30506d4441232edc4241358bb2' 
  AND token = 'OV2BlAGM5oYttRZt9UMBf3rbhkQ4SzprHfbW8psXfO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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