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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f786ad6fafd85b9d110c8bcb19c9c4b494f446e70ad2508d0c9bbcf3a31ccd0' 
  AND token = 'L3ZPMf5L7NCVEOGMTaUt+JRLUgF8vJ7lyIiSzLYGMQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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