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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5ad34ee0fede0aa2df93c3f2b6e3ca53b765385d1656b3500c59c863cec4b0d9' 
  AND token = 'L7rWYXYZuVns+iInXmtWXQ5O8bHlApiHkrv0sAJFRBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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