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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3846916b0f89cc7bcfa5246da9084d89ba5e4ffd888c7f2289c9cf6c5090d7d' 
  AND token = '6PMPTWdfAlp9H7fyP3zSi0+5Ra/6nbmzkldo+t/+eb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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