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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0278888b425d7bc87c24b381c187bf8abd9d97d5613d5139988ca8f7c3faefb2' 
  AND token = 'gr0BdrmhnfEhsieM/PLm/Rx281j+Q8+jsU+Rsw+VqLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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