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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cb3543cff32065f93efbb08fa0ddd674ff5e0d6774db968a83801c00055d22d5' 
  AND token = 'Is5DoR4yzZcPfaaLguVI0Ubtu1oLaR9mB+wc2owo2S4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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