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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c203dd94e72f70a2e8a539def92f01db8f6308c78c384e9b03e8da2dd8c5d0b6' 
  AND token = 'e5HSI7FR/MjSvYRqiMtxP989Od8AcVeKDoNxTw9or+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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