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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8eeb1f1c158ea28032c72dc68e844f9f35e4d869789623bee4e892ac6d6e4102' 
  AND token = '165HLyHPX2mVz2M9nw1ApE6FHEPCProCKeTCo1bnMH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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