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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ce55bcc749bfda1d1859710d08c9bfdb19d029e59ff6945533e92f7a0582d692' 
  AND token = 'eKmiAZSLqgfwobDOIbp+Fb2R8WFqGdIDtm/ynuU3sjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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