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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35853991ddb8f5a2bcedcb51b65c4a01ac9a3def96c2310957a157c51e40550a' 
  AND token = 'ru/4fsWDKN7JQqdTe5gOhdGWqZAHrNdjhUe3qVFMEj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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