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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad68c7dbb7f6303ce905f52285df02809ab03f2b06e6c5eeffd4c5d073c4f599' 
  AND token = 'ct6QZ8mbNTSKrWjCyLHqPTrgVYIuUx4XfcMv6BdKPtA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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