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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9fb35a8845900ea63f5a0e4c6e10700b1c3f5837a8ccaf019c2df6a3c6ff1f0b' 
  AND token = 'd8fcrGBpGjNxOW7zbf1+W9CpnU2ygz5SfgPoLL/Sh70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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