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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c8cd2400f827bcbe6b1ae567d36914cbf5c3d603de27b3a5a12cbb3d3cd97aa' 
  AND token = 'gM30xa6pBFc+/YaZ+155xQQ/ODxtpiTDanUAruPQWAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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