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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6f52137cd4ad93f003da1b07384b6ac4be6c833ed9ff180a67e91dde997e61c' 
  AND token = 'BrBcYKKv3T1ycbtGAyG1asDHRp8YgNCDKSF5LXSP4Pk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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