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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a7f75bcd2579ff6d78319afdd3279ef79f911a88d4e9efdb3e0e51a3c0a947b' 
  AND token = 'YE9Ag+9clYuBRquOXwvWHd+kVIeN9pkQjdHe9zcrFDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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