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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '856e5b59fc4b2fe4cf3514d890f69fb54eb20f462d01571a9cb43fb54295ccf3' 
  AND token = '9xT+Ykzi1P+sF6cuqFhYtNhVqi3EiOPxoPcKszomrYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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