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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b294366c812e4389033189a5fe50d0532195d7e360797a8313f4154ae3aceb49' 
  AND token = 'rtAv9tA+rMvUD/N3m/2DJfgMNSbTpQSYylH2Mmglo8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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