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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7fc91d8fc5cf951d1ae4ca2e502dac79701e265b1d468c327f81a1de9650b7ac' 
  AND token = 'YytjPtKBJ0AUS17uMXRWhW9dOp5dUkBbHA4Q6EBnF+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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