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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9ba7f250a1ec3b31c2b1a9a15027a33be5ffb092462a10838bbbf951bdf85194' 
  AND token = 'KZAbutbAiNEAnXyK0Y9Dki37qj1hZBVMfWaFTs4PU5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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