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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7a68d667a9051bb96e287faed9e70392a501442ae611bd99233a2d59d834cb9f' 
  AND token = 'S2k+GBN0XxtcfoRAH4q2VAS5cQihI8hgkXfC57I1lng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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