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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '62c41d3aba68fcfb5dbb8a0e060d63fb56e3a87f7d92290179a41b8ae3cb9636' 
  AND token = 'MR1RkI7d3MNp5tnFdaHKsVy+fKoJqQqMFlNluU+VGzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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