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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c1ed470df74b10459046c8b8aed809b6ddc8d1ca4c687df33d1965cc3ac1e4ab' 
  AND token = 'U5qKfi+fmB7P2/Cs5ke9UopOmsChT0uu2bGbOzpsmLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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