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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7f5d4556cae2128707b1488f1b0d6ee44dbd4877e68de5fcb1843c472835ec80' 
  AND token = 'nfDpNYE6sQhwmofQEurIbCLtmhAiEmv+AH/wtgRmtx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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