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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2bc71d9b225c82074267df2aa8eb54b93eb9fd8d8ec365e9cd08edcca0f40773' 
  AND token = 'Wr8B9M4qc0ifWVdq3JxKBstFDbvMQ+yPc0N9UWwwOr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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