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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6b6a0f5afa495024dab154dfd45afb6690913cda4df86a4d43ae95f1b023c06f' 
  AND token = 'C9CTBZ0/TdWEQ1dISJlUSM27l0lf4It2OoLwNwPU+Bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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