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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '83641175b7dc54845f1ee4ebac0b5c517dfef977b955f2f9516bf5d1b5817e8e' 
  AND token = 'I6pMUejEklVLhqWyoI/JjpgWhivhgupup6gfuwSTpeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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