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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4d35fa2fd479bc1fe032b890c4463eb61884a42c1e1adea528e80e8f4d3ee44a' 
  AND token = 'ircK5y99+QInXUZffjpxK7rBlAvT+MT2f6RP3s7uIig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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