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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a230f65c2b581cf78b6616aa939d78df8f1cf4e232c42f589a13b981b8ff1ef0' 
  AND token = 'rs7SKCer1+5ZjsKIca7z1jkErUH1Gy/v2NNiDm2Xv+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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