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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff5e5fea5f98ec9bb908e04f41ecd20ef108ad16cd8e7d141891104a213ad20e' 
  AND token = 'UqFvDVzxtRDmtu7/sk25lgNfAeRBuHcDGxE0pU1K58Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}