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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b3f0c1fb14fd08d0d20819160c7a3b82b60b3fda9c9a0412af5333121354b5ef' 
  AND token = 'AkqIpzMf+NdGJoDtgTMyDLMAt4PcYxGJxMRPatIOt90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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