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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '335d0f1de3662b2d1c5a5f13ed059490eb45de7616b1e384d9727d5e4b32888a' 
  AND token = 'RQ5Ynw8kqEjGN9h1GbBCrQ8L+2q5ZDSUD1Ubs3XdAkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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