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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8290a0485c1faac2c2b0b55448eb953b2582996e0b9c4d02cc2cd7d745ff4e8d' 
  AND token = 'X8pinhj8NoYUnFo5xiONvLy6ecCFvK9JOFGKyJdhJDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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