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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd969cb9f9c427147b5dc01ea8fca2ff7cb03b38c224e8fb233ae3e8d5969dfa6' 
  AND token = 'sUJk/kPPR5fC+FfsRcAm6uBXjy7URF9WdFcF7RDU47A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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