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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7571519ea1755957c176dea40e1a06c696fc9d93bddf8a2e99fb1d37c244b79' 
  AND token = 'RHRgKxoDaKlJ+DDJEz7QotPs1o2Dg16ojFeTmnoR26U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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