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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '93608c6b43fb91f3fada83cfd986275716e8f1a992e8ab7f89f60a640967e69c' 
  AND token = '6A1a5ONHAPjYywo7bt6FEuUcyVulBA6C/Z+imXjrn38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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