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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a76968dd3f4e4a5cc294a4061369b99e0a03eeb283c6a05a0c5b50ae9223d500' 
  AND token = 'hYpwnmOuTFAuFpMUXahKISpSg6NNFmgKIPIgv3g9wYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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