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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b9b4972f0546a94c81c4255db63eecd7227232173da07d1e249534cd0bfa165a' 
  AND token = '+md8o4liXKOQGPOaJHV4V+5COriAMRTPGF1KiiQow6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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