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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a2ecb1e680689c942ead786bd9203bdaa09c8d85e013508b455b2f028264ad' 
  AND token = 'vZCrKDLJkjWfsP+Ica7Ufmqwr9iN7DFNzQvk4OJQT1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}