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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f139971c8448062a3dcf37c65fd6b7a64f4d20d0302d4956ac522c884f2363ff' 
  AND token = '4/2rpt+8jXvAljw/S0juv0a8XH9NlLtUMiuc4rLDRPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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