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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b34c58f9bd7966dc3c3a80b40a895ad2c1d5d16fd073794247bacbe3885272f9' 
  AND token = 'lfdj2Lz/g0ojeUiS5lBsMw6Nkz3tbZeKZRUMqQ0/mTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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