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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3b6816d999d69853dfa0bdf0b48515f6e8aaf47039556f3313991f8fcbff779d' 
  AND token = '/bKS/cj6ZsPoWKaraON12XhXHWb4PhfN6SgJN/LnYmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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