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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef7942fb5586ee8a063ec316fe397c670f0d3f93d72ae8753f3764923a8d21bb' 
  AND token = 'Pk8Kh5XRMcohe8lcd7GpaxFrVAWrK9NTdSQ2DCR+iGE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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